Tramesan elicits durum wheat defense against the septoria disease complex

The Septoria Leaf Blotch Complex (SLBC), caused by the two ascomycetes Zymoseptoria tritici and Parastagonospora nodorum, can reduce wheat global yearly yield by up to 50%. In the last decade, SLBC incidence has increased in Italy; notably, durum wheat has proven to be more susceptible than common wheat. Field fungicide treatment can efficiently control these pathogens, but it leads to the emergence of resistant strains and adversely affects human and animal health and the environment. Our previous studies indicated that active compounds produced by Trametes versicolor can restrict the growth of mycotoxigenic fungi and the biosynthesis of their secondary metabolites (e.g., mycotoxins). Specifically, we identified Tramesan: a 23 kDa α-heteropolysaccharide secreted by T. versicolor that acts as a pro-antioxidant molecule in animal cells, fungi, and plants. Foliar-spray of Tramesan (3.3 μM) on SLBC-susceptible durum wheat cultivars, before inoculation of causal agents of Stagonospora Nodorum Blotch (SNB) and Septoria Tritici Blotch (STB), significantly decreased disease incidence both in controlled conditions (SNB: –99%, STB: –75%) and field assays (SNB: –25%, STB: –30%). We conducted these tests were conducted under controlled conditions as well as in field. We showed that Tramesan increased the levels of jasmonic acid (JA), a plant defense-related hormone. Tramesan also increased the early expression (24 hours after inoculation-hai) of plant defense genes such as PR4 for SNB infected plants, and RBOH, PR1, and PR9 for STB infected plants. These results suggest that Tramesan protects wheat by eliciting plant defenses, since it has no direct fungicidal activity. In field experiments, the yield of durum wheat plants treated with Tramesan was similar to that of healthy untreated plots. These results encourage the use of Tramesan to protect durum wheat against SLBC

Oligosaccharides derived from tramesan: Their structure and activity on mycotoxin inhibition in aspergillus flavus and Aspergillus carbonarius

Food and feed safety are of paramount relevance in everyday life. The awareness that different chemicals, e.g., those largely used in agriculture, could present both environmental prob-lems and health hazards, has led to a large limitation of their use. Chemicals were also the main tool in a control of fungal pathogens and their secondary metabolites, mycotoxins. There is a drive to develop more environmentally friendly, \u201cgreen\u201d, approaches to control mycotoxin contamination of foodstuffs. Different mushroom metabolites showed the potential to act as control agents against mycotoxin production. The use of a polysaccharide, Tramesan, extracted from the basidiomycete Trametes versicolor, for controlling biosynthesis of aflatoxin B1 and ochratoxin A, has been previously discussed. In this study, oligosaccharides obtained from Tramesan were evaluated. The purified exopolysaccharide of T. versicolor was partially hydrolyzed and separated by chromatography into fractions from disaccharides to heptasaccharides. Each fraction was individually tested for myco-toxin inhibition in A. flavus and A. carbonarius. Fragments smaller than seven units showed no sig-nificant effect on mycotoxin inhibition; heptasaccharides showed inhibitory activity of up to 90% in both fungi. These results indicated that these oligosaccharides could be used as natural alternatives to crop protection chemicals for controlling these two mycotoxins

Abiotic stress in Potato Tuber: Analysis of some factors related to Oxidative Stress

In previous studies about different kinds of stress (wounding and cold storage) below bud potato tuber (Solanum tuberosum L. cv. Kennebec), a relationship between lipoperoxides (LOOH) and indole-3-acetic acid (IAA) has been shown (Fabbri et al., 2000; J. Exp. Bot. 51: 1267-75; Reverberi et al., Free Rad. Res. 2001, 35: 833-841). Endogenous LOOH, originated from lipoxygenase (LOX) action and exogenously added, increased the formation of IAA at different times after wounding (20 min) and after cold storage (from 90 to 180 days). Furthermore LOX inhibitors (salicylhydroxamic acid, SHAM, 1mM and nordihydroguaiaretic acid NDGA, 1 mM) inhibited this effect confirming the correlation between LOOH and IAA in potato tubers. It is known that also the biosynthesis of jasmonic acid (JA) and its derivative methyljasmonate (MeJA) is related with the formation of LOOH. In this work a possible correlation between MeJA and IAA in potato tubers sliced below bud has been studied. MeJA (10 mM) added on potato tuber slices enhanced, after 24 h the production of IAA and IAA, added at the same concentration, increased the formation of JA and MeJA 20-30 min after wounding. These results, obtained by GC/MS analyses, showed a possible direct or indirect correlation between MeJA and IAA